The overall objective of this grant is to define the mechanisms and dietary factors that control plasma lipoproteins and their interaction with the arterial wall. 125I-labelled lipoproteins will be used to study the fractional and total catabolic rates of the different lipoproteins in squirrel and Cebus monkeys and rabbits. Variation in diet will be used to induce different lipoprotein concentrations. Flux of lipoproteins will be used as an index of the importance of different tissues for overall catabolism. Rabbit hepatocytes will also be used for the study of lipoprotein uptake and catabolism, as well as for lipoprotein synthesis from labelled leucine, palmitate, and choline. The importance of the acute and habitual diet on very low density lipoprotein and chylomicron synthesis will be studied in vivo with Triton WR 1339. We will also continue studies of the cholesterol gallstones that develop in squirrel monkeys on certain diets.